1. Field of the Invention
The present invention relates to an image processing apparatus and image processing control method that are applied in a digital copying machine, facsimile device, a printer or other devices, a complex machine (MFP) having a combination of some or all of the processing functions of these devices or a scanner, and other image data processing devices.
2. Description of the Background Art
In an image processing apparatus such as a digital copying machine, processing functions for, for example, line-to-line correction, shading correction, MTF (spatial frequency characteristic) filtering, gamma conversion and gradation processing are required. Furthermore, in a complex machine (MFP), a copy function, scanner function, facsimile function, printer function and the like are required in one image processing apparatus.
In a conventional image processing apparatus, generally a plurality of processing functions are realized by using data processing hardware (ASIC) having a plurality of independent dedicated processing sections, as described in, for example, Japanese Patent Application Laid-Open No. H8-274986 or U.S. patent application Ser. No. 5,715,070. An advantage of using such data processing hardware having a plurality of dedicated processing sections is that speed performance is excellent. However, since this hardware is designed in hard logic, a disadvantage is that it lacks flexibility in changing and adding functions. As a solution to this problem, sometimes a programmable device such as a DSP (digital signal processor) is used. An advantage of using a programmable device such as a DSP is that it can deal with flexibility in changing/adding processing functions by downloading again a processing program inside the DSP. However, since this programmable device is used for software processing, a disadvantage is that it lacks speed performance, compared to dedicated hard logic. Moreover, a processing program memory and processing data memory are required in the conventional programmable device as much as the number of processes to be performed, thus such programmable device has another disadvantage of high expense.
The image processing apparatus for an ASIC and the image processing apparatus for DSP have advantages and disadvantages as described above, thus they are used separately.
On the other hand, in a recent complex machine (MFP), the process flows are diversified and complicated because of the enhanced copy function, scanner function, facsimile function, printer function and the like thereof. The reason is that various processing functions need to be installed in order to respond to various user requests. Furthermore, because of strong user requests for image performance, the number of image processes tends to increase in order to obtain high-quality pictures. It should be noted that diversity and complexity of the process flows can also be said in, not only the complex machine, but also devices such as a digital copying machine, facsimile device and printer, and other image data processing devices.
For this reason, there is a problem that the hardware section for actually performing image processing, such as an ASIC, is enlarged, increasing the production cost. Especially, the data processing hardware such as an ASIC is configured in which a plurality of dedicated blocks for processing and dedicated memories for processing are disposed as much as the number of required processing functions in the hardware, as described above, thus it is difficult to reduce the cost while maintaining the required processing functions. Moreover, dedicated hardware logic is constituted inside of the hardware beforehand to realize the processing functions, thus a fundamental problem is that this hardware lacks flexibility in subsequent changing and adding the processes.
Moreover, although the programmable device such as a DSP is not as excellent as the ASIC in terms of the speed performance and costs, the largest advantage thereof is the high degree of freedom that the functions can be programmed freely to respond to each user request. Specifically, changing and adding processes can be realized easily by programming a desired processing function and downloading the program code to the DSP or the like. However, in the conventional image processing apparatus using the programmable device such as a DSP, program memories and data memories are required as much as the number of processes when executing a plurality of processing functions, as described above, thus the problem is that the size of the DSP or the like is enlarged, further increasing the costs, compared to the ASIC and the like. Also, required capacity of the data memory tends to increase more and more as the image data expands, thus the cost increase is inevitable.